Apparatus for cracking hydrocarbons



1. w. COAST, JR- APPARATUS FOR CRACKING HYDROCARBONS. APPLICATION FILED SEPT. 27, I917.

1,349,815. PatentedAug 17,1920.

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1 3 A iv W UNITED STATES PATENT OFFICE.

JOHN W. COAST, JR., OF TULSA, OKLAHOMA, ASSIGNOR TO THE PROCESS COMPANY, OF TULSA, OKLAHOMA, A CORPORATION OF MARYLAND.

APPARATUS FOR CRACKING HYDROCARBONS.

To all whom it may concern Be it known that I, JOHN W. CoAsT, J r., a citizen of the United States of America, a resident of Tulsa, in the county of Tulsa, State of Oklahoma, have invented certain new and useful Improvements in Apparatus for Cracking Hydrocarbons, of which the following is a full, clear, and exact description, reference being had to the accompanying drawing, forming a part of this specification.

This invention relates to improvements in apparatus for cracking hydrocarbons, the main object being to protect cracking stills from the injurious effects of carbon or tarry substances known in the art as coke and coke-forming matter.

Another object is to circulate the oil undergoing distillation, thereby economizing in the use of fuel, maintaining the oil at a substantially uniform temperature throughout the still, and enabling the temperature "to be raised quickly at the beginning of the distilling operation. I

A further object is to enable the apparatus to remain in service for a considerable period of-time without cooling the still or removing the residue.

In the preferred form of the invention, all of these desirable results are accomplished by circulating a small stream of the hydrocarbon liquid from the heated lower portion of the still, through a screen or filter wherein the coke-forming matter is separated from the oil, and then discharging the filtered oil into the main body of oil. While the oil is undergoing distillation under high pressure and at a high temperature, the

heavy coke-forming fractions drop by gravity to the bottom of the still, and infollowing the ordinary practice, the coke or carbon is permitted to accumulate on the still bottom, directly above the fire. One of the important problems in this, art lies in the elimination of large bodies of coke or carbon, from the hottest parts of cracking stills. The coke or carbon is an insulating substance, preventing the free transmission of heat from the still bottom to the oil, thus decreasing the efficiency of the heating medium, and-when a sufi'icient quantity of the insulatingsubstance accumulates in the still, the still bottom becomes red hot. Some im mediate steps must then be taken to avoid Specification of Letters Patent. Patented Aug 1'7 1920 Application filed. September 27, 1917.

Serial No. 193,455.

Fig. II is an enlarged longitudinal sec- 7 tion of the still.

Fig. III is an enlarged section of the strainer or filter. In the apparatus shown to illustrate the 1nvent1on, a large cylindrical still 1 is arranged above a heating chamber 2, and connected by means of a vapor pipe 3, to an air cooled reflux condenser 4c. 5 designates a vapor pipe leading from the reflux condenser 4 to a main condensing coil 6, from which the low boiling point product is recovered. The condensing coil 6 is preferably arranged in a water tank 7.

The apparatus herein shown is particularly, adapted for use in cracking high boiling point products of distillation such, for example, as distillates or residues resulting from the distillation of crude petroleum.

the vapor pipe 5. The pressure in the still is preferably greater than 50 pounds per square inch, for example, about 80 pounds per square inch, and the temperature of the contents of the still preferablyranges from about 600 F. to 800 F. Heat generated in the heating chamber 2 is transmitted directly through the still bottom to the liquid contents of the still. The low boiling point vapors passing from the liquid, flow through the vapor pipe 3 and reflux condenser 4. to the pipe 5, leading to the main condenser 6 from which the low boiling point product is recovered. The relatively high boiling point fractions are condensed in the vapor pipe 3 or in the condenser 4, such fractions being returned, by gravity, through the vapor pipe 3. The heating chamber 2 may be provided with a grate 8 on which a bed of fuel is maintained.

Inthe preferred form of the invention,

'an elongated intake pipe 9, arranged in the lower portion of the still, is provided with inlet ports 10 at various points through its length) 11 designates a rotary pump connected to the intake pipe 9, and provided with a discharge pipe 12 leading to a strainer or filter A, the latter being provided witha discharge pipe 13. The pump and filter, as well as the pipes 9, 12 and 18, are preferably located in the still and submerged in the liquid contents thereof. A power shaft 14, passing through a stuffing box 15 atone end of the still, may be rotated to actuate the pump 11. A pinion 16 fixed to the inner end of shaft 14:, meshes with an operating Wheel 17 on the pump,

andthis shaft 14 may be rotated by transmitting power. to a wheel 18 at the exterior of the still.

The filter, or strainer, A comprises a screen 19 arranged in a housing 20 wherein the coke-forming matter is separated from the oil. The filter or strainer may also include a layer of fullers earth 22 between the mineral wool 21 and the top wall of the housing 20. To obtain the highest efliciency, a large filter should be used and its capacity should enable the distillation to be carried on for a considerable period of time without removing the coke-forming matter from the filter.

While the oil is undergoing distillation, the rotary pump 11 is operated continually, thereby drawing oil and coke-forming matter through the ports 10 in the intake pipe near the hot still bottom, the stream of oil and coke-formin matter being drawn to the pump 11, and discharged through the pipe 12, to the filter A. The free carbon, or coke-forming matter, accumulates in the filter A, and the filtered oil is constantly discharged from the pipe 13 to the main body of oil in the still. A relatively small stream of oil is thus maintained in circulation in the large main body of oil, and the coke-forming matter is "filtered from the small internal stream and collected in the housing 20, instead of being permitted to accumulate on the hot still bottom. It will now be understood that this invention entirely eliminates the danger usually due to an accumulation of coke or carbon in the still. thereby greatly increasing the life of the still, increasing the efiiciency by taking away the heat insulating matter from the place at which the heat is transmitted throu 11 the still, and enabling the still to be rec iarged and run continuously for a considerable period of time without cooling the apparatus, and Without removing the residue.

By forcibly circulating a relatively small stream of oil in the main body of the oil. as herein disclosed, a general circulation of all of the oil is maintained. The hot oil ontering the pipe 9 is drawn toward ne end of the still, then upwardly to the pump and thereafter discharged toward the opposite end of the still. Owing to the manner in which the oil is circulated, a substantially uniform temperature is maintained at all points throughout the oil, the heat being transmitted quickly from the still bottom to the entire body of oil. This is an advantage at all times during the distilling operation and more particularly at the beginning of the operation, at which time it is desirable to obtain the necessary high temperature throughout the still as quickly as possible.

I claim.-

in an apparatus for cracking petroleum hydrocarbons, a fire-heated cracking still wherein a body of hydrocarbon oil is confined, the bottom of the still being exposed to the fire, means for separating coke-forming matter from said body of oil, said means including an intake conductor arranged within the'still and having an inlet near the heated lower portion of the still, a filter communicating with said intake conductor, said filter having an outlet for the discharge of filtered oil to the main body of oil, and a pump whereby oil is circulated through said intake conductor and filter, said pump and filter being arranged within the still, and pump operating means at the exterior of the still.

In testimony that I claim the foregoing l hereunto aflix my si nature.

JOH w. COAST, JR. 

